The present invention relates to a technology for a high pressure injection nozzle member for working a work and more particularly, to a material for a high pressure injection nozzle adapted for an abrasive water jet and made of a hard material or cemented carbide alloy having a high abrasion proof or resistance property.
Recently, there has been provided various mechanical and electric machines, instruments, elements and parts having complicated and precise structures, which result in complicated manufacturing and assemblying processes and this tendency has also been accelerated.
Moreover, since it is required for these machines, instruments, elements and parts to be manufactured, inspected and maintained so as not to change their function with the lapse of time, the precision and performance thereof have been more highly required. In addition, since these machines, instruments, elements and parts are provided with various cut surfaces and surfaces to be cut or worked and it is required to have excellent durability for the maintenance or the like, these surfaces are to be cut or worked for more precise performance.
In order to satisfy these requirements in recent technology, it has also be required to study and develop new materials, and accordingly, new technology or techniques for cut working, cutout separation working or the like working have been studied and developed.
In a conventional cut working or cutout separation working technology, there has been, provided various means, for example, mechanical means such as cutter or the like, thermal fusing means utilizing a gas burner or arc, for example, or other physical cutting means utilizing plasma, for example. However, in the recent technology, such requirements have been made severe for the cut working of complicated portions and the separation cutting of molecular binding portions, and accordingly, in order to avoid decomposition of a base material or to avoid generation of burrs or the like, a non-contact working method has been required. The conventional technology is however not sufficient for satisfying such requirements for practical use.
There has been further provided a cutting technology, in order to satisfy these requirement, utilizing water jet, in which the cutout separation working for coats, drilling working, grooving working, cutting working of the material, and the like working are carried out by means of water jet of highly pressurized beam form having about several hundred or several tens of hundreds bars. This method has been utilized for cutting metal material as well as wood or synthetic resin material and, therefore, has been studied and developed. For example, is proposed an abrasive type water jet nozzle, for improving the working efficiency, by mixing abrasive material of fine grain or particle structure into the high pressure water jet. However, even in such technology, there remains many problems for hardware or software techniques because of the use of the high pressure water jet.
In the meantime, the cut working caused by such a water jet involves substantially no generation of heat in the actual cut working, resulting in no decomposition or no deformation of the material to be cut, thus being preferred for the extremely smooth cut working of the material, satisfying the desire on the design. In this viewpoint, such water jet cut working technique is one promising cut working technique for so-called a net shape or near net shape working. Accordingly, such cut working techniques have been also studied from before and are in partial practical use.
However, the abrasive type water jet cut working has not been widely utilized until recently for cut working requiring extremely high cutting performance.
The characteristic feature of cemented carbon alloy or hard material is generally determined in accordance with an amount of a binder such as Co, and the composition and kind of hard carbon, the diameter of each grain composing the hard carbon, an amount of carbon contained in the alloy, and the like. These factors are determined, in actuality, in accordance with required characteristics--such as hardness, abrasion proof property, tenacity, anti-corrosion property, strength against high temperature, or the like, based on the practical use.
In another aspect, various characteristic features may be required for tools to be used. However, it is considerably difficult to satisfy all of these requirements or factors, and accordingly, these factors have been selectively weighed and utilized in accordance with the material to be cut and the actual cutting conditions.
Generally, the hardness and the tenacity of the cemented carbon alloy or hard material have relatively opposing relationship with respect to WC (tungsten carbide) grains and the amount of Co. Namely, the hardness is made higher as the grain diameter becomes smaller and the amount of Co in the binding phase decreases. On the contrary, the tenacity is made high in proportion to the increasing of the Co amount.
The cemented carbon alloy or the hard material, as described hereinabove, has been utilized for cutting tools, tools having an abrasion proof property, or the like, and these tools have been designed by basically considering the hardness of the alloy, whereas the tools have been also designed by considering to a certain extent the tenacity in the viewpoint of preventing the tools from being bent or deformed and chipping.
In the conventional technology, usually, the material for the abrasive water jet nozzle has been selected from the cemented carbon alloy material or hard material for a tool, but, regarding the hardness thereof, alloys having a hardness slightly smaller than the possibly maximum hardness have been selected. Accordingly, the cemented carbon alloy material or the hard material for the water jet nozzle are greatly worn in elapse of time and the durability of such cemented carbon alloy or hard material as the abrasive water jet nozzle material is merely several hours in the practical use, resulting in poor application for satisfying such recent requirements as described hereinbefore.
A main factor for the severe abrasion of the nozzle such as water jet nozzle will be based on erosion of the nozzle material with respect to the cemented carbon alloy or the hard material due to grains or powders of fine metallic particles in the water jet.
In the meantime, there is known, as a specific sintered alloy, so-called a binder-less alloy such as WC-TaC-TiC of hard material including no Co for improving the anti-corrosion property, but such a specific sintered alloy is of a binder-less structure, and accordingly, the hardness is naturally increased and an alloy having HRA 94.0 or near has been utilized in practical use.
The abrasion proof property of the nozzle such as described water jet nozzle has been improved in comparison with that of the conventionally utilized cemented carbon alloy or hard material for a generally used tool in proportion to the degree of increased hardness. However, there exists a considerable gap between the actual degree of durability and the object or required degree thereof, thus not being satisfactory.
As described above, in view of various viewpoints, it may be said that the existing material for the water jet nozzle is not provided with the desired combination of optimum hardness and tenacity, and accordingly, further improvement or development has been highly required.
Consequently, as described hereinbefore, nozzles such as abrasive water jet nozzles are subjected to severe jetting abrasion in practical use due to the erosion of fine grains or particles contained in the water jet, so that the abrasion of the material is very remarkable, and particularly, an inlet mouth portion and an outlet portion of the water jet nozzle are subjected to extremely violent abrasion. This results in the expansion of the inner diameter of the water jet nozzle in elapse of time, which will further result in the degradation of the cutting efficiency and performance with respect to a workpiece to be cut.
As countermeasure to the above defects, it is necessary to exchange with a new nozzle every relatively short time period of practical use, resulting in the lowering of the working efficiency.